Q: Are there no stacks of gold or treasure that would contain money lying around to pick up either?
A: Money is lying on the roads, but in very small amounts (say, 250gp). Treasure Chests contain a little bit more (say, 1000gp) but they're monster-guarded. Also all of these are only on newly-explored areas (exactly like in HoMMV) and are not renewable.
One pecular "real-time" thing is that you can in fact steal a guarded item without fighting. Just wait till monster who is supposed to guard the item, and does so by walking to and fro, moves somewhere sideways. Or play tease-and-run game: when a monster sees a player, he is eager to pursue him and forgets his guarding business for a while. But this "game designers-approved cheating" is a really time-consuming and boring process. And besides, as I mentioned, Chests are not very rich. You also can get some two grands or even less for doing a Quest. But a decent battle with about equal-strenght Monster would give me (at my current level) about 10 grands in trophies.
So really, to get rich you have to fight well
Maybe there are other ways, but I'm not aware of them.